docs(README): Update release badges & ClusterRole aggregation

[doronkg]

What this PR does / why we need it?

This PR adds 2 small fixes to README.md:

1. Adds discovery reference for ClusterRole aggregation (added in fix: ClusterRole Aggregation #221).
2. Separates release badges for kor & Helm.

Current:

Updated:

PR Checklist

• This PR adds K8s exceptions (false positives)
• This PR adds new code
• This PR includes tests for new/existing code
• This PR adds docs

Notes for your reviewers

I used https://shields.io/badges/git-hub-release to test the badges.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.39%. Comparing base (01ce4a6) to head (1a35afc).
Report is 4 commits behind head on main.

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #340   +/-   ##
=======================================
  Coverage   42.39%   42.39%           
=======================================
  Files          61       61           
  Lines        3236     3236           
=======================================
  Hits         1372     1372           
  Misses       1644     1644           
  Partials      220      220           

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